CN110622036A

CN110622036A - Selecting a wireless communication channel based on a signal quality metric

Info

Publication number: CN110622036A
Application number: CN201780090730.7A
Authority: CN
Inventors: D·格里斯多夫; S·A·丹维森; M·奥默尔; 朴云峰; O·克拉维茨; T·曼库; C·V·奥列卡斯
Original assignee: Cognitive Systems Inc
Current assignee: Cognitive Systems Inc
Priority date: 2017-03-16
Filing date: 2017-10-26
Publication date: 2019-12-27
Anticipated expiration: 2037-10-26
Also published as: US10004076B1; JP7105245B2; US10111228B2; KR20190127728A; US20180270821A1; WO2018165738A1; CA3055423A1; EP3596496A1; EP3596495A1; CN110622035B; EP3596495B1; KR102460633B1; KR102457631B1; JP2020515151A; CA3055336A1; CN110622035A; JP7043509B2; KR20190132372A; EP3596496A4; EP3596496B1

Abstract

In a general aspect, a wireless communication channel is selected based on a signal quality metric. In some aspects, a first wireless communication device receives a first set of signals based on wireless signals transmitted through a space on a first wireless communication channel from a second wireless communication device. A signal quality metric value is calculated based on the first set of signals, and a second wireless communication channel is selected based on a determination that the value of the signal quality metric does not meet a quality criterion for the motion detection process. The first wireless communication device receives a second set of signals based on wireless signals transmitted through the space from the second wireless communication device on a second wireless communication channel, and performs motion detection processing to detect motion of an object in the space based on the second set of signals.

Description

Selecting a wireless communication channel based on a signal quality metric

Priority requirement

This application claims priority from U.S. application 15/706,193 entitled "Selecting Wireless Communication Channels Based on Signal Quality Metrics" filed on 15.9.2017 and U.S. provisional application 62/472,375 entitled "Selecting Wireless Communication Channels for motion Detection Signals Using criteria Metrics" filed on 16.3.2017, which are incorporated herein by reference.

Background

The following description relates to motion detection.

Motion detection systems have been used to detect movement of objects in, for example, a room or outdoor area. In some exemplary motion detection systems, infrared or optical sensors are used to detect movement of objects in the field of view of the sensor. Motion detection systems have been used in security systems, automated control systems, and other types of systems.

Drawings

Fig. 1A is a diagram illustrating an exemplary wireless communication system.

Fig. 1B is a diagram illustrating an exemplary wireless network device communicating over a wireless communication channel.

Fig. 1C is a diagram illustrating an exemplary wireless modem communicating over multiple communication paths.

Fig. 2 is a diagram illustrating an exemplary motion detection signal.

Fig. 3A and 3B are diagrams illustrating exemplary wireless signals communicated between wireless communication devices.

Fig. 4 is a flow diagram illustrating an exemplary process for selecting a wireless communication channel based on a signal quality metric.

Fig. 5 is a flow diagram illustrating another exemplary process for selecting a wireless communication channel based on a signal quality metric.

Detailed Description

In some described aspects, a wireless communication channel is selected based on a signal quality metric. For example, in some cases, a signal quality metric is calculated based on motion detection signals received by the wireless communication device over a wireless communication channel (e.g., a frequency channel or a code channel). The signal quality metric is used to estimate the quality of communications between various wireless communication devices over a wireless communication channel. The signal quality metric may be based on a channel response for a space traversed by the wireless signal, a signal-to-noise ratio of a signal received by the wireless communication device, a number of packets accepted or rejected as input to the motion detection process, other types of quality metrics, or a combination thereof. In some examples, the signal quality metric is based on a time period that accepts a minimum number of signals as inputs to the motion detection process. In some examples, the signal quality metric is based on a number of communication paths between the transmitting wireless communication device and the receiving wireless communication device (e.g., between a particular transmit antenna and receive antenna pair). In some instances, weighting may be applied to factors considered in determining the signal quality metric.

In some implementations, the wireless communication device (or other device coupled to the wireless communication device, e.g., a server remote from the device) may select a wireless communication channel for the wireless communication device to communicate on based on the signal quality metric. For example, the receiving wireless communication device may determine whether the calculated signal quality metric is above or below a predetermined threshold (which may be a quality criterion for the motion detection process). If the signal quality metric is not above the threshold, a new wireless communication channel is selected for communication. In some examples, the receiving wireless communication device may send a message indicating a new wireless communication channel. For example, the receiving wireless communication device may instruct the transmitting wireless communication device to "move" to a different wireless communication channel that the receiving wireless communication device has selected and transmit a motion detection signal on the selected channel. In some instances, the process is repeated for the selected channel. For example, a signal quality metric may be determined for a motion detection signal received on a selected channel, and if the signal quality metric is below a threshold, the other channel is selected. If the signal quality metric for the new channel is above the threshold, the device may continue to communicate on that channel. In some examples, the wireless communication devices may periodically check the signal quality metrics of other channels to ensure that they are communicating on the highest quality wireless communication channel.

In some implementations, a wireless communication device determines an optimal wireless communication channel for communication based on signals transmitted on a plurality of wireless communication channels. A signal quality metric may be calculated for each channel and one of the channels may be selected based on a comparison of the signal quality metrics of the plurality of channels. For example, it may be determined whether a signal quality metric of one of the wireless communication channels is better than a signal quality metric of a currently used wireless communication channel. If a channel with a higher signal quality metric is found, the channel is selected and the wireless communication device begins communicating on the channel. Otherwise, the wireless communication device may continue to communicate on the current wireless communication channel. In some instances, the wireless communication devices may do this periodically to ensure that they communicate on the highest quality wireless communication channel.

In some implementations, to reduce or avoid problems when detecting motion, the wireless communication device may suspend the channel selection process when motion is currently being detected. Once motion is no longer detected, the channel selection process may continue. In some implementations, the calculated average of the signal quality metric may be used in the channel selection process to "smooth" the behavior of the signal quality metric, as interference may sporadically appear and disappear.

In some implementations, wireless communication devices may each have multiple transmit or receive antennas, and thus may communicate between these antennas over multiple communication paths. The antenna of each wireless communication device may form one of a plurality of signal hardware paths, and each communication path may be defined by a signal hardware path from a transmitting wireless communication device and a signal hardware path from a receiving wireless communication device, respectively. For example, a transmitting wireless communication device may have two transmit antennas (e.g., T1 and T2), and a receiving wireless communication device may have two receive antennas (e.g., R1 and R2). Wireless communication devices may communicate over up to four communication paths (e.g., T1- > R1, T1- > R2, T2- > R1, and T2- > R2), respectively. A signal quality metric may be determined for each communication path used by the wireless communication device. In examples where each device has two transmit antennas and two receive antennas, up to four signal quality metrics may be determined for motion detection signals communicated between wireless communication devices, and the channel selection process may include selecting a communication path based on the signal quality metrics calculated for each communication path.

In some implementations, a number of viable communication paths between wireless communication devices is determined, and a wireless communication channel is selected based on the number of viable communication paths on the channel. For example, a wireless communication channel having the largest number of feasible communication paths may be selected for communication. In some implementations, the wireless communication channel may be selected based on both the number of feasible communication paths and the value of the signal quality metric. For example, a wireless communication channel may be selected based on having the highest signal quality metric among the channels having the smallest number of viable communication paths. In a system having multiple wireless communication devices (e.g., three or more wireless communication devices), a different channel may be selected for each wireless communication link based on the number of feasible communication paths or channel credit values. For example, one link between a pair of wireless communication devices may operate on a first wireless communication channel and other links between different pairs of wireless communication devices may operate on a second wireless communication channel.

In some instances, the systems and techniques described here may provide one or more advantages. For example, motion may be detected using wireless signals transmitted through space. Motion can be detected more efficiently by selecting the wireless communication channel with the best signal quality metric. Further, the links between pairs of wireless communication devices may operate on different channels.

Fig. 1A is a diagram illustrating an exemplary wireless communication system 100. The exemplary wireless communication system 100 includes three wireless communication devices-a first wireless communication device 102A, a second wireless communication device 102B, and a third wireless communication device 102C. The exemplary wireless communication system 100 may include additional wireless communication devices and other components (e.g., additional wireless communication devices, one or more network servers, network routers, network switches, cables or other communication links, etc.).

The example wireless communication devices 102A, 102B, 102C may operate in a wireless network, for example, according to a wireless network standard or other type of wireless communication protocol. For example, the wireless network may be configured to operate as a Wireless Local Area Network (WLAN), a Personal Area Network (PAN), a Metropolitan Area Network (MAN), or other type of wireless network. Examples of WLANs include networks configured to operate in accordance with one or more standards of the 802.11 family of standards developed by IEEE, etc. (e.g., Wi-Fi networks). Examples of PANs include PANs that are based on short-range communication standards (e.g.,near Field Communication (NFC), ZigBee), millimeter wave communication, and the like.

In some implementations, the wireless communication devices 102A, 102B, 102C may be configured to communicate in a cellular network, for example, according to a cellular network standard. Examples of cellular networks include networks configured according to the following standards: 2G standards such as Global System for Mobile (GSM) and enhanced data rates for GSM evolution (EDGE) or EGPRS; 3G standards such as Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), Universal Mobile Telecommunications System (UMTS), and time division synchronous code division multiple access (TD-SCDMA); 4G standards such as Long Term Evolution (LTE) and LTE-advanced (LTE-a); and so on.

In some cases, the wireless communication devices 102A, 102B, 102C may be or may include standard wireless network components; for example, a conventional Wi-Fi access point or other type of Wireless Access Point (WAP) may be used in some cases. In some cases, other types of standard or conventional Wi-Fi transmitter devices may be used. The wireless communication devices 102A, 102B, 102C may be implemented without Wi-Fi components; for example, other types of standard or non-standard wireless communication may be used for motion detection. In some cases, the wireless communication devices 102A, 102B, 102C may be, or may be part of, a dedicated motion detection system.

As shown in fig. 1A, exemplary wireless communication device 102C includes a modem 112, a processor 114, a memory 116, and a power supply unit 118; any of the wireless communication devices 102A, 102B, 102C in the wireless communication system 100 may include the same, additional, or different components, and these components may be configured to operate as shown in fig. 1A or otherwise. In some implementations, the modem 112, processor 114, memory 116, and power supply unit 118 of the wireless communication device are housed together in a common housing or other assembly. In some implementations, one or more components of the wireless communication device may be housed separately, e.g., in a separate housing or other assembly.

The exemplary modem 112 may communicate (receive, transmit, or both) wireless signals. For example, modem 112 may be configured to communicate Radio Frequency (RF) signals formatted according to a wireless communication standard (e.g., Wi-Fi). The modem 112 may be implemented as the example wireless network modems 112A, 112B shown in fig. 1C, or may be implemented in other ways (e.g., with other types of components or subsystems). In some implementations, the example modem 112 includes a radio subsystem and a baseband subsystem. In some cases, the baseband subsystem and the radio subsystem may be implemented on a common chip or chipset, or they may be implemented in a card or other type of assembly device. The baseband subsystem may be coupled to the radio subsystem, for example, by wires, pins, wires, or other types of connections.

In some cases, the radio subsystem in modem 112 may include radio frequency circuitry and one or more antennas. The radio frequency circuitry may include, for example, circuitry for filtering, amplifying, or otherwise conditioning an analog signal, circuitry for up-converting a baseband signal to an RF signal, circuitry for down-converting an RF signal to a baseband signal, etc. Such circuitry may include, for example, filters, amplifiers, mixers, local oscillators, and the like. The radio subsystem may be configured to communicate radio frequency wireless signals over a wireless communication channel. Referring to the example shown in fig. 1C, the radio subsystem may include a radio chip 113, an RF front end 115, and antennas 117, 119. The radio subsystem may include additional or different components. In some implementations, the radio subsystem may be or include radio electronics (e.g., an RF front end, a radio chip, or similar component) from a conventional modem (e.g., from a Wi-Fi modem, a pico base station modem, etc.). In some cases, the radio subsystem includes multiple signal hardware paths (e.g., multiple antennas). In some implementations, the modem 112 (or any of its components, including, for example, the radio chip 113, the RF front end 115, and the antennas 117, 119 in fig. 1C) may be implemented using commercial products or components (e.g., a commercial Wi-Fi modem, a commercial cellular modem, a commercial bluetooth modem, or commercially available components thereof).

In some cases, the baseband subsystem in modem 112 may, for example, include digital electronics configured to process digital baseband data. As an example, the baseband subsystem may include the baseband chip 111 shown in fig. 1C. The baseband subsystem may include additional or different components. In some cases, the baseband subsystem may include a Digital Signal Processor (DSP) device or other type of processor device. In some cases, the baseband system includes digital processing logic to operate the radio subsystem, to communicate wireless network traffic through the radio subsystem, to detect motion based on motion detection signals received through the radio subsystem, or to perform other types of processing. For example, the baseband subsystem may include one or more chips, chipsets, or other types of devices configured to encode signals and communicate the encoded signals to the radio subsystem for transmission, or to identify and analyze data encoded in signals from the radio subsystem (e.g., by decoding the signals according to a wireless communication standard, by processing the signals according to a motion detection process, or otherwise).

In some examples, the radio subsystem in the example modem 112 receives baseband signals from the baseband subsystem, upconverts the baseband signals to Radio Frequency (RF) signals, and transmits the RF signals wirelessly (e.g., via an antenna). In some examples, the radio subsystem in the example modem 112 receives radio frequency signals wirelessly (e.g., through an antenna), down-converts the radio frequency signals to baseband signals, and sends the baseband signals to the baseband subsystem. The signals exchanged between the radio subsystem and the baseband subsystem may be digital signals or analog signals. In some examples, the baseband subsystem includes conversion circuitry (e.g., digital-to-analog converters, analog-to-digital converters) and exchanges analog signals with the radio subsystem. In some examples, the radio subsystem includes conversion circuitry (e.g., digital-to-analog converters, analog-to-digital converters) and exchanges digital signals with the baseband subsystem.

In some cases, the baseband subsystem of the example modem 112 may communicate wireless network traffic (e.g., data packets) in a wireless communication network via the radio subsystem on one or more network traffic channels. The baseband subsystem of modem 112 may also send or receive (or both) signals (e.g., motion detection signals or motion detection signals) over the dedicated wireless communication channel through the radio subsystem. In some instances, the baseband subsystem, for example, generates motion detection signals for transmission to detect the space used for motion. In some examples, the baseband subsystem processes received motion detection signals (based on signals that transmit motion detection signals through the space), for example, to detect motion of objects in the space. For example, the baseband subsystem of modem 112 may be programmed (e.g., via software) to perform one or more of the operations (e.g., calculate signal quality metrics, etc.) of the example processes 400, 500 of fig. 4, 5.

The example processor 114 may, for example, execute instructions to generate output data based on data inputs. The instructions may include programs, code, scripts, or other types of data stored in memory. Additionally or alternatively, the instructions may be encoded as pre-programmed or re-programmable logic circuits, logic gates, or other types of hardware or firmware components. The processor 114 may be or include a general purpose microprocessor, as a special purpose coprocessor or other type of data processing device. In some cases, the processor 114 performs high-level operations for the wireless communication device 102C. For example, the processor 114 may be configured to execute or interpret software, scripts, programs, functions, executables, or other instructions stored in the memory 116. In some implementations, the processor 114 may be included in the modem 112. In some implementations, the processor 114 executes instructions for implementing the processes 400, 500 of fig. 4, 5.

The example memory 116 may include computer-readable media, such as volatile memory devices, non-volatile memory devices, or both. The memory 116 may include one or more read only memory devices, random access memory devices, cache memory devices, or a combination of these and other types of memory devices. In some examples, one or more components of the memory may be integrated or otherwise associated with other components of wireless communication device 102C. The memory 116 may store instructions executable by the processor 114. The instructions may include instructions for selecting a wireless communication channel for communication based on the signal quality metric, such as by using the processes 400, 500 of fig. 4, 5, and so forth.

The exemplary power supply unit 118 provides power to the other components of the wireless communication device 102C. For example, other components may operate based on power provided by the power supply unit 118 through a voltage bus or other connection. In some implementations, the power supply unit 118 includes a battery or a battery system, such as a rechargeable battery. In some implementations, the power supply unit 118 includes an adapter (e.g., an AC adapter) that receives an external power signal (from an external source) and converts the external power signal to an internal power signal that is conditioned for components of the wireless communication device 102C. The power supply unit 118 may include other components or operate in other manners.

In the example shown in fig. 1A, the wireless communication devices 102A, 102B transmit wireless signals (e.g., according to a wireless network standard, a motion detection protocol, or otherwise). For example, the wireless communication devices 102A, 102B may broadcast wireless signals (e.g., reference signals, beacon signals, status signals, etc.), or they may transmit wireless signals addressed to other devices (e.g., user equipment, client devices, servers, etc.), and the other devices (not shown) as well as the wireless communication device 102C may receive the wireless signals transmitted by the wireless communication devices 102A, 102B. In some cases, the wireless signals transmitted by the wireless communication devices 102A, 102B are repeated periodically, such as according to a wireless communication standard or otherwise.

In the example shown, the wireless communication device 102C, operating in a state defined by modem parameters, processes wireless signals from the wireless communication devices 102A, 102B and detects movement of objects in the space to which the wireless signals access. For example, the wireless communication device 102C may perform the example processes 400, 500 of fig. 4, 5, or other types of processes for detecting motion. The space to which the wireless signal is accessed may be an indoor or outdoor space, which may include, for example, one or more areas that are fully or partially enclosed, open areas that are not enclosed, and the like. The space may be or may include the interior of a room, a plurality of rooms or buildings, etc. In some cases, for example, the wireless communication system 100 may be modified such that the wireless communication device 102C may transmit wireless signals and the wireless communication devices 102A, 102B may process the wireless signals from the wireless communication device 102C to detect motion.

The wireless signals used for motion detection may include, for example, beacon signals (e.g., bluetooth beacons, Wi-Fi beacons, other wireless beacon signals), other standard signals generated for other purposes according to a wireless network standard, or non-standard signals generated for motion detection or other purposes (e.g., random signals, reference signals, etc.). In some examples, the wireless signal propagates through the object (e.g., a wall) before or after interacting with the moving object, which may allow for detection of movement of the moving object without an optical line of sight between the moving object and the transmitting or receiving hardware. Based on the received signal, the third wireless communication device 102C may generate motion detection data. In some instances, the third wireless communication device 102C may communicate the motion detection data to other devices or systems (such as security systems, etc.), which may include a control center for monitoring movement within a space such as a room, building, outdoor area, etc.

In some implementations, the wireless communication devices 102A, 102B may be modified to transmit motion-sounding signals (e.g., the motion-sounding signals described below with respect to fig. 2) on separate wireless communication channels (e.g., frequency channels or code channels) in accordance with wireless network traffic signals. For example, the third wireless communication device 102C may know the modulation applied to the payload of the motion detection signal and the type or data structure of the data in the payload, which may reduce the amount of processing by the third wireless communication device 102C for motion sensing. The header may include additional information such as, for example, an indication of whether motion was detected by other devices in the communication system 100, an indication of the type of modulation, an identification of the device sending the signal, and so forth.

In the example shown in fig. 1A, the wireless communication link between the third wireless communication device 102C and the first wireless communication device 102A may be used to probe the first motion detection field 110A, and the wireless communication link between the third wireless communication device 102C and the second wireless communication device 102B may be used to probe the second motion detection field 110B. In some examples, the third wireless communication device 102C detects motion in the motion detection fields 110A, 110B by processing received signals based on wireless signals sent by the wireless communication devices 102A, 102B, respectively. For example, when the person 106 shown in fig. 1A moves in the first motion detection field 110A, the third wireless communication device 102C may detect motion based on signals received at the third wireless communication device 102C based on wireless signals transmitted by the first wireless communication device 102A.

In some instances, the motion detection fields 110A, 110B may include, for example, air, solid materials, liquids, or other media through which wireless electromagnetic signals may propagate. In the example shown in fig. 1A, the first motion detection field 110A provides a wireless communication channel between the first wireless communication device 102A and the third wireless communication device 102C, and the second motion detection field 110B provides a wireless communication channel between the second wireless communication device 102B and the third wireless communication device 102C. In some aspects of operation, wireless signals transmitted over a wireless communication channel (separate from or shared with a wireless communication channel used by network traffic) are used to detect movement of objects in space. The object may be any type of static or movable object and may be animate or inanimate. For example, the object may be a human being (e.g., the human being 106 shown in fig. 1A), an animal, an inorganic object, or other apparatus, device, or assembly, an object used to define all or part of a boundary of a space (e.g., a wall, door, window, etc.), or other type of object.

Fig. 1B is a diagram illustrating exemplary wireless communication devices 102A, 102C communicating over a wireless communication channel 108. The wireless communication channel 108 may be used to communicate data between the wireless communication devices 102A, 102C. In the example shown, wireless communication device 102A transmits wireless signals on one or more of the wireless communication channels 108, and these wireless signals are received by wireless communication device 102C. The wireless communication channel 108 may be defined by a wireless communication standard or other wireless communication protocol. In the example shown in fig. 1A, the wireless communication devices 102A, 102C support communication over N different wireless communication channels 108. In some implementations, the wireless communication channels include N-X different network traffic channels for carrying network traffic (e.g., data packets) communicated between the wireless communication devices 102A, 102C, and X different motion detection channels for carrying motion detection signals (e.g., motion detection signals formatted like the motion detection signal 202 of fig. 2) between the wireless communication devices 102A, 102C. In some cases, a wireless network system or a separate wireless network device may support other types of wireless communication channels, or additional wireless communication channels of the same type (e.g., multiple different motion detection channels). In some cases, two or more adjacent wireless communication channels may be combined to form one motion detection channel, which may increase the frequency bandwidth of the motion detection channel.

In some implementations, the wireless communication channel 108 is a frequency channel. For example, the wireless communication channels 108 may each occupy or otherwise correspond to a different frequency bandwidth within a licensed or unlicensed band of the wireless spectrum. The frequency channels may include overlapping bandwidths or non-overlapping bandwidths. In some Wi-Fi standards, each frequency channel corresponds to a different center frequency and has a frequency bandwidth. In an example, the center frequencies are 5MHz apart (e.g., 2.412GHz, 2.417GHz, 2.422GHz, etc.), and each channel has a bandwidth of 20 MHz. The modem 112A of the wireless communication device 102A may be configured to communicate on other types of frequency channels (e.g., having other frequency intervals or frequency bandwidths).

In some implementations, the wireless communication channel 108 is a code channel. For example, each wireless communication channel may correspond to a different spreading code and operate within a common frequency range in a licensed or unlicensed band of the wireless spectrum. In some cases, spreading codes are used to generate spread spectrum transmissions on individual code channels, e.g., to avoid interference between code channels in the same frequency range. In some types of Code Division Multiple Access (CDMA) standards, each code channel corresponds to a different channel code that is combined with a data signal to generate a channel-coded signal. In an example, each channel code is a pseudo-random binary code. In some cases, multiple (e.g., some or all) code channels share the same frequency bandwidth. The modem 112A of the wireless communication device 102A may be configured to communicate over other types of coded channels.

In some implementations, the wireless communication channel 108 includes a frequency channel and an encoded channel. For example, the network traffic channel may be a frequency channel and the motion detection channel may be a code channel. As another example, the network traffic channel may be a code channel and the motion detection channel may be a frequency channel.

As described below, one of the channels 108 may be selected based on a signal quality metric. The signal quality metric may attempt to quantify the ability of communications to be exchanged over the channel 108 between the wireless communication devices 102A, 102C. In some cases, the signal quality metric may be different for each channel 108, as different channels 108 may have different sources of interference. In some implementations, a new channel 108 is selected if the value of the signal quality metric for the currently used wireless communication channel 108 does not meet the quality criteria of the motion detection process (e.g., the value of the signal quality metric is below a threshold). In some implementations, channels are selected for communication based on the values of the signal quality metrics of the various channels 108. For example, the channel 108 having the highest signal quality metric value may be selected for communication.

FIG. 1C is a diagram illustrating exemplary wireless modems 112A, 112B communicating over multiple communication paths 121-124. In some examples, each wireless modem 112 may be implemented as a card, chip, chipset, or other type of device. The modem may generally include the radio subsystem and baseband subsystem, as well as software or firmware for one or more wireless communication standards or other protocols. In some cases, the modem includes hardware, software, or firmware (or a combination thereof) to support multiple wireless communication standards (e.g., 3G and LTE). In some cases, modem 112 may be implemented using a commercial product or component (e.g., a commercial Wi-Fi modem, a commercial cellular modem, a commercial bluetooth modem, or a commercially available component thereof).

The exemplary wireless modem 112 shown in fig. 1C may operate as described above. For example, wireless modem 112 may transmit wireless signals over one or more wireless communication channels (e.g., a network traffic channel and a dedicated motion detection channel) and may detect motion of an object, for example, by processing the received signals using modem parameters (e.g., settings related to baseband chip 111, radio chip 113, or RF front-end chip 115). In some instances, the example wireless modem 112 may operate in other manners.

The exemplary wireless modems 112 communicate with each other over a plurality of communication paths 121-124. Each communication path is defined by a signal hardware path of modem 112A and a signal hardware path of modem 112B. For example, in the example shown, communication path 121 is defined by antenna 117A of modem 112A and antenna 117B of modem 117B, communication path 122 is defined by antenna 117A of modem 112A and antenna 119B of modem 117B, communication path 123 is defined by antenna 119A of modem 112A and antenna 117B of modem 117B, and communication path 124 is defined by antenna 119A of modem 112A and antenna 119B of modem 117B. In some examples, modem 112 may communicate via various communication paths by transmitting signals from both antennas 117, 119 (e.g., transmitting the same signal at each antenna), and the signals may be received by other modems using one or both of antennas 117, 119 (e.g., depending on interference in the respective communication paths). In some implementations, the signal hardware path includes multiple antennas of the modem. For example, the communication path may be defined by a plurality of antennas at the first modem and a plurality of antennas at the second modem.

The exemplary wireless modem 112 shown in fig. 1C includes a baseband chip 111, a radio chip 113, and a Radio Frequency (RF) front end 115. The wireless modem 112 may include additional or different features, and the components may be arranged as shown or otherwise. In some implementations, the baseband chip 111 includes components and performs the operations of the baseband subsystem described with respect to the exemplary modem 112 shown in fig. 1A. In some implementations, the baseband chip 111 may process the in-phase and quadrature signals (I and Q signals) from the radio chip 113 to extract data from the received wireless signal. The baseband chip 111 may control the radio chip 113 or perform other operations. In some cases, baseband chip 111 may be implemented as a Digital Signal Processor (DSP) or other type of data processing device.

In some implementations, the radio chip 113 and the RF front end 115 include components and perform the operations of the radio subsystem described with respect to the example modem 112 shown in fig. 1A. In some implementations, the radio chip 113 may generate in-phase and quadrature signals (I and Q signals) in, for example, a digital or analog format based on the received wireless signals. In some implementations, the RF front end 115 may include one or more filters, RF switches, couplers, RF gain chips, or other components for conditioning radio frequency signals for transmission or processing.

In some examples, modem 112 processes received signals based on motion detection signals sent through space by other modems. For example, modem 112A may process a received signal based on a motion detection signal transmitted by modem 112B. These received signals may be referred to as motion detection signals. Processing the received signal may include: the motion detection signal is received at one or both of antennas 117, 119, conditioned (e.g., filtered, amplified, or downconverted) at radio chip 113 or RF front end 115, and digitally processed at baseband chip 111. Modem 112 may utilize one or more modem parameters that indicate one or more settings of baseband chip 111, radio chip 113, or RF front end 115. For example, the modem parameters may include one or more of a gain setting, an RF filter setting, an RF front end switch setting, a DC offset setting, an IQ compensation setting, or other settings for radio chip 113 or RF front end 115, or a digital DC correction setting, a digital gain setting, a digital filter setting, or other settings for baseband chip 111.

In the radio subsystem of the exemplary modem 112 shown in fig. 1C, the gain setting (e.g., using an Automatic Gain Control (AGC) loop) controls the amount of gain provided to the RF signals received by the antennas 117, 119 at the RF front end 115; the RF filter settings (e.g., based on the expected bandwidth of the signal to be received at the antenna 117) control the bandwidth filter in the RF front end 115; the RF front end switch settings control which RF filters or antenna switches are enabled in the RF front end 115 (e.g., select a particular signal from one of a plurality of antennas); the DC offset setting controls a DC signal correction amount applied to the baseband signal in the radio chip 113 (for example, using a DC offset loop); and the IQ compensation setting controls the amount of IQ phase correction applied to the signal by the radio chip 113. In the baseband subsystem of the exemplary modem 112 shown in fig. 1C, the digital DC correction settings control the amount of DC signal correction applied to the digital signal in the baseband chip 111; the digital gain setting controls the amount of gain applied to the digital signal in the baseband chip 111; and the digital filter settings control which filters are applied to the digital signal in the baseband chip 111.

In some examples, if the received signal has a relatively weak amplitude, the gain setting may increase the amount of gain applied to the received signal (before processing by the radio chip 113). Conversely, if the received signal has a relatively strong amplitude, the gain setting may reduce the amount of gain applied to the received signal. As another example, if the desired signal has a relatively wide bandwidth of about 40MHz, the RF filter arrangement may arrange an RF filter in the RF front end 115 to allow the 40MHz signal to pass from the antenna 117 to the radio chip 113. As another example, if a DC signal (a signal having ω ═ 0 and a positive or negative amplitude) is present in the downconverted baseband signal, the DC offset setting may allow a DC correction signal to be applied to the downconverted baseband signal in radio chip 113 to remove the DC signal. As another example, in the case where the in-phase signal and the quadrature signal (I signal and Q signal) do not have a 90-degree phase difference (e.g., 93-degree difference), an IQ correction signal may be applied to the signals to achieve a desired 90-degree phase difference.

Fig. 3A and 3B are diagrams illustrating exemplary wireless signals communicated between wireless communication devices 304A, 304B, 304C. The wireless communication devices 304A, 304B, 304C may be, for example, the wireless communication devices 102A, 102B, 102C shown in fig. 1A, or other types of wireless communication devices. The example wireless communication devices 304A, 304B, 304C transmit wireless signals through the space 300. The exemplary space 300 may be completely or partially closed or open at one or more boundaries of the space 300. The space 300 may be or may include an interior of a room, a plurality of rooms, a building, an indoor area or an outdoor area, and so forth. In the example shown, the first wall 302A, the second wall 302B, and the third wall 302C at least partially enclose the space 300.

In the example shown in fig. 3A and 3B, the first wireless communication device 304A is operable to repeatedly (e.g., periodically, intermittently, at predetermined, non-predetermined, or random intervals, etc.) transmit wireless signals. The transmitted signal may be formatted like the motion detection signal 202 of fig. 2 or otherwise. The second wireless communication device 304B and the third wireless communication device 304C are operable to receive signals based on signals transmitted by the wireless communication device 304A. The wireless communication devices 304B, 304C each have a modem (e.g., modem 112 shown in fig. 1C) configured to process the received signals to detect movement of objects in the space 300.

As shown, the object is in a first position 314A in FIG. 3A, and the object has moved to a second position 314B in FIG. 3B. In fig. 3A and 3B, the moving object in the space 300 is represented as a human being, but the moving object may be other types of objects. For example, the moving object may be an animal, an inorganic object (e.g., a system, apparatus, device, or assembly), an object used to define all or part of a boundary of the space 300 (e.g., a wall, door, window, etc.), or other type of object.

As shown in fig. 3A and 3B, a plurality of exemplary paths of wireless signals transmitted from the first wireless communication device 304A are shown with dashed lines. Along the first signal path 316, the wireless signal is transmitted from the first wireless communication device 304A and reflected by the first wall 302A toward the second wireless communication device 304B. Along the second signal path 318, wireless signals are transmitted from the first wireless communication device 304A and reflected by the second wall 302B and the first wall 302A toward the third wireless communication device 304C. Along the third signal path 320, the wireless signal is transmitted from the first wireless communication device 304A and reflected by the second wall 302B toward the third wireless communication device 304C. Along a fourth signal path 322, wireless signals are transmitted from the first wireless communication device 304A and reflected by the third wall 302C toward the second wireless communication device 304B.

In fig. 3A, along a fifth signal path 324A, a wireless signal is transmitted from the first wireless communication device 304A and reflected by an object at the first location 314A toward the third wireless communication device 304C. Between fig. 3A and 3B, the surface of the object moves from a first position 314A to a second position 314B in the space 300 (e.g., a distance away from the first position 314A). In fig. 3B, along a sixth signal path 324B, a wireless signal is transmitted from the first wireless communication device 304A and reflected by an object at the second location 314B toward the third wireless communication device 304C. As the object moves from the first position 314A to the second position 314B, the sixth signal path 324B depicted in FIG. 3B is longer than the fifth signal path 324A depicted in FIG. 3A. In some examples, signal paths may be added, removed, or otherwise modified due to movement of objects in space.

The exemplary wireless signals shown in fig. 3A and 3B may undergo attenuation, frequency shift, phase shift, or other effects through their respective paths and may have portions that propagate in other directions, e.g., through walls 302A, 302B, and 302C. In some examples, the wireless signal is a Radio Frequency (RF) signal. The wireless signals may include other types of signals.

In the example shown in fig. 3A and 3B, the first wireless communication apparatus 304A may repeatedly transmit a wireless signal. In particular, fig. 3A shows a wireless signal transmitted from a first wireless communication device 304A at a first time, and fig. 3B shows the same wireless signal transmitted from the first wireless communication device 304A at a second, later time. The transmission signal may be transmitted continuously, periodically, at random or intermittent times, etc., or by a combination thereof. The transmit signal may have multiple frequency components in a frequency bandwidth. The transmit signal may be transmitted from the first wireless communication device 304A in an omnidirectional manner, in a directional manner, or in other manners. In the example shown, the wireless signals traverse multiple respective paths in space 300, and the signals along each path may become attenuated due to path loss, scattering, or reflection, etc., and may have a phase or frequency shift.

As shown in fig. 3A and 3B, the signals from the various paths 316, 318, 320, 322, 324A, and 324B combine at the third wireless communication device 304C and the second wireless communication device 304B to form a received signal. Due to the effect of multiple paths in space 300 on the transmit signal, space 300 may be represented as a transfer function (e.g., a filter) that inputs the transmit signal and outputs the receive signal. As an object moves in space 300, the attenuation or phase shift affecting the signal in the signal path may change, and thus the transfer function of space 300 may change. In the case where it is assumed that the same wireless signal is transmitted from the first wireless communication apparatus 304A, if the transfer function of the space 300 changes, the output of the transfer function (i.e., the reception signal) will also change. The change in the received signal can be used to detect movement of the object.

Mathematically, the transmission signal f (t) transmitted from the first wireless communication apparatus 304A can be described according to equation (1):

wherein ω is_nRepresenting the frequency of the nth frequency component of the transmitted signal, c_nA complex coefficient representing the nth frequency component, and t represents time. When the transmission signal f (t) is transmitted from the first wireless communication apparatus 304A, the output signal r from the path k can be described by equation (2)_k(t)：

Wherein alpha is_n,kRepresenting the attenuation factor (or channel response; e.g., due to scattering, reflection, and path loss) for the nth frequency component along path k, and_n,krepresenting the signal phase for the nth frequency component along path k. The received signal R at the wireless communication device can then be described as all output signals R from all paths to the wireless communication device_k(t), i.e., as shown in formula (3):

substituting formula (2) for formula (3) to obtain formula (4):

the received signal R at the wireless communication device may then be analyzed. The received signal R at the wireless communication device may be transformed to the frequency domain, for example, using a Fast Fourier Transform (FFT) or other type of algorithm. The transformed signal may represent the received signal R as a series of n complex values, where (n frequencies ω_nOf) each corresponds to a complex value. For frequency omega_nFrequency component of (2), complex value H_nCan be represented by the following formula (5):

for a given frequency component ω_nComplex value of (H)_nIndicating the frequency component omega_nThe relative amplitude and phase shift of the received signal. Complex value H when an object moves in space_nChannel response due to space alpha_n,kIs changed. Thus, a detected change in channel response may be indicative of movement of an object within the communication channel. In some instances, noise, interference, or other phenomena may affect the channel response detected by the receiver, and the motion detection system may reduce or isolate such effects to improve the accuracy and quality of the motion detection capability.In some implementations, the overall channel response may be expressed as:

in some instances, the channel response h for the space may be determined, for example, based on mathematical estimation theory_ch. For example, the candidate channel response (h) may be used_ch) To modify the reference signal R_efThe maximum likelihood method may then be used to select and receive the signal (R)_cvd) The best matching candidate channel. In some cases, the reference signal (R)_ef) And candidate channel response (h)_ch) Obtaining an estimated received signalThen changes the channel response (h)_ch) So as to estimate the received signalThe squared error of (c) is minimized. This may be done, for example, with optimization criteria

Shown mathematically as:

the minimization or optimization process may utilize adaptive filtering techniques such as Least Mean Squares (LMS), Recursive Least Squares (RLS), Batch Least Squares (BLS), and the like. The channel response may be a Finite Impulse Response (FIR) filter or an Infinite Impulse Response (IIR) filter, etc.

As shown in the above equation, the received signal can be considered as the convolution of the reference signal and the channel response. Convolution means that the channel coefficients have a correlation with each delayed copy of the reference signal. Thus, the convolution operation as shown in the above equation shows that the received signal appears at different delay points, where each delayed replica is weighted by the channel coefficient.

In some aspects, a signal quality metric for a received signal may be determined based on a channel response. For example, reference signal (R) may be referenced_ef) Applying the determined channel response (h) of the space_ch) To generate an estimated received signalThe estimated received signalBased on the channel response (e.g., based on the reference signal (R) as described above_ef) And channel response (h)_ch) Convolution of) of the received signal. Can use the estimated received signalAnd the actual received signal (R)_cvd) A signal quality metric is calculated. In some examples, for example, the signal quality metric is based on calculating the actual received signal (R)_cvd) And estimating the received signalAnd the actual received signal (R)_cvd) A value Q determined by the dot product of the differences (e.g., set equal to the value Q, calculated from the value Q, representing the value Q, etc.), such as:

in some implementations, the number of viable communication paths between wireless communication devices may be determined. Each communication path may include an antenna pair or other signaling hardware for transmitting and receiving wireless signals. For example, a transmitting wireless communication device may have two transmit antennas (e.g., T1 and T2), and a receiving wireless communication device may have two receive antennas (e.g., R1 and R2). Wireless communication devices may communicate over up to four communication paths (e.g., T1- > R1, T1- > R2, T2- > R1, and T2- > R2), respectively. The communication paths that are feasible signal paths may be specified based on the throughput of the communication paths. For example, the receive rate score may be defined according to equation (10):

RxRateScore＝max(0，MaxRxRate-PathRxRate)#(10)

where MaxRxRate is the minimum throughput required for proper data transfer in the communication path, and PathRxRate is the measured throughput of the communication path. The measured throughput may be based on a number of packets received by the apparatus over the communication path over a period of time. For example, in some instances, throughput is measured as the total number of packets received on a path per second. As another example, throughput is measured as the number of "accepted" packets per second (e.g., based on a signal quality metric value as described below). If the PathRxRate is less than the MaxRxRate, then the path may be designated as a viable communication path. In some instances, the feasible path score may be determined according to equation (11):

ViablePathScore＝RxRateScore*Qweight#(11)

where Qweight is a weighting factor applied to the RxRateScore described above based on the communication quality on the path (e.g., using the value Q in equation (9) above).

In some implementations, the signal quality metric is based on a channel score value (e.g., set equal to the channel score value, calculated from the channel score value, representing the channel score value, etc.), wherein the channel score value is based on a number of viable communication paths of the wireless communication channel (e.g., set equal to the number, calculated from the number, representing the number, etc.). For example, each wireless communication channel may have a channel score value defined according to equation (12):

where a and b are weighting factors applied to the ViblePath score value and the ViblePath value of i paths on the channel, where ViblePath is a Boolean value defined according to equation (13):

ViablePath＝RxRateScore>0#(13)

other calculations may be used to determine the signal quality metric. In some cases, for example, the absolute value or amplitude of the dot product or other calculated value is used as a signal quality metric for the received signal. In some cases, the signal quality metric is a correlation index or other type of signal quality metric. In some cases, the signal quality metric is determined based on a signal-to-noise ratio (SNR) of the received signal.

In some cases, the received signal may be "rejected" by the wireless communication device. For example, in some implementations, the motion detection process may include a quality criterion for the signal. Received signals that do not meet the quality criteria may be rejected (e.g., discarded or ignored) and not considered in determining whether motion has occurred in the space 300. The signal may be accepted or rejected as input to the motion detection process based on a signal quality metric (e.g., value Q as described by equation (9)). For example, in some cases, motion is detected using only a subset of the received signals having a value Q above a particular threshold. In some implementations, the signal quality metric is based on the number of signals accepted as inputs to the motion detection process. For example, the calculated signal quality metric may be weighted based on the percentage of the signal that is accepted as input to the motion detection process over a period of time. Further, in some implementations, the signal quality metric is based on a time period that accepts a minimum number of signals as inputs to the motion detection process. For example, the calculated signal quality metric may be weighted according to the time it takes to obtain the minimum number of accepted signals (e.g., the weight drops if it takes a longer time).

In some implementations, such as systems having three or more wireless communication devices (e.g., the system of fig. 1A or the systems of fig. 3A-3B), the number of viable communication paths, signal quality metrics, or both may be considered in selecting a wireless communication channel for motion detection. For example, consider the example shown in table 1, which shows signal quality metric information for a link between a wireless communication device (device 0) and two other wireless communication devices (i.e., device 1 and device 2):

TABLE 1

Channel with a plurality of channels	Device 1	Device 2
			1	[7,500]	[1,100]
2	[4,300]	[4,300]
			3	[1,100]	[7,500]

Where x in the [ x, y ] symbols represents the number of viable communication paths for the channel, and y in the [ x, y ] symbols represents the value of a signal quality metric for the channel (e.g., the channel score described in equation (12) above). In the example shown in Table 1, the number of feasible communication paths ranges from 0 to 8, and the value of the signal quality metric ranges from 0 to 600. Selecting channel 1 for communication between all devices in this example would provide relatively good communication quality between device 0 and device 1 (because the number of viable communication paths is high and the signal quality metric value is high), but relatively poor communication quality between device 0 and device 2 (because the number of viable communication paths is low and the signal quality metric value is low). Also, selecting channel 3 for communication between all devices in this example would provide a relatively good communication quality between device 0 and device 2, but a relatively poor communication quality between device 0 and device 1. Selecting channel 2 may provide sufficient communication quality between wireless communication devices because the number of viable communication paths is moderate and the signal quality metric value is moderate.

In some implementations, to enhance the quality of communication between wireless communication devices, the links between pairs of wireless communication devices may operate on different wireless communication channels. For example, in the example shown in table 1, device 0 and device 1 may communicate on channel 1, while device 0 and device 2 may communicate on channel 3. Since the wireless communication device is operable to communicate on only one channel at a time, device 0 (in this example) may be configured to switch its operation between the respective wireless communication channels to employ this technique.

In some implementations, the number of viable wireless communication devices may be determined for each wireless communication channel based on the signal quality metric and the number of viable communication paths. The number of viable wireless communication devices may be determined based on a threshold value of a signal quality metric on each link between the wireless communication devices. Referring to the example shown in table 1, channel 2 is determined to have two viable wireless communication devices, e.g., based on each link between the wireless communication devices having a signal quality metric value greater than 250. Similarly, channels 1 and 3 in table 1 are each determined to have one viable wireless communication device based on the same threshold value of the signal quality metric value being 250. In some implementations, the number of viable wireless communication devices for each channel is based on the channel having the smallest number or percentage of viable communication paths. For example, the number of viable wireless communication devices for a channel may be determined based on how many links between wireless communication devices have 50% or higher of the available communication paths. In some implementations, the number of viable wireless communication devices for each channel is based on both a minimum number or percentage of viable communication paths and a minimum signal quality metric. For example, the number of viable wireless communication devices for the channel may be determined based on both how many links between the wireless communication devices have (1) a signal quality metric value above a threshold (e.g., 250 as in the example above), and (2) a number of viable communication paths above a threshold (e.g., at least two viable communication paths). In some implementations, the wireless communication channel for motion detection may be selected based on the number of viable devices. For example, the wireless communication channel with the highest number of viable devices may be selected for use.

Fig. 4 is a flow diagram illustrating an exemplary process 400 for selecting a wireless communication channel based on a signal quality metric. In some examples, process 400 may be implemented to detect motion of an object in space based on signals transmitted over a selected wireless communication channel. The operations in the example process 400 may be performed by a data processing apparatus (e.g., the processor 114 of the example wireless communication device 102C of fig. 1A) to detect motion based on signals received at a wireless communication device (e.g., the wireless communication device 102C of fig. 1A). The exemplary process 400 may be performed by other types of devices. For example, the operations of process 400 may be performed by a system for receiving signals other than wireless communication device 102C (e.g., a computer system connected to wireless communication system 100 of fig. 1A that aggregates and analyzes signals received by wireless communication device 102C).

The example process 400 may include additional or different operations, and the operations may be performed in the order shown or in other orders. In some cases, one or more of the operations illustrated in FIG. 4 are implemented as a process comprising multiple operations, sub-processes, or other types of routines. In some cases, the operations may be combined, performed in other orders, performed in parallel, iterated or otherwise repeated, or performed in other ways.

At 402, a first set of signals is received at a wireless communication device over a wireless communication channel. The wireless communication channel may be a frequency channel or a code channel, and the signal may be based on a wireless signal transmitted through the space by other (transmitting) wireless communication devices. For example, referring to the example shown in fig. 1A, the signal may be a wireless signal transmitted by one (or both) of the wireless communication devices 102A, 102B and received at the third wireless communication device 102C. In some implementations, the wireless communication device receiving the signal may be the same device that originally transmitted the wireless signal through the space. In some implementations, the received signal may be a motion detection signal based on a motion detection signal transmitted through space. The motion detection signal may be received over a wireless communication channel used for network traffic or a different wireless communication channel dedicated to motion detection.

At 404, a value of a signal quality metric is calculated for a wireless communication channel. The signal quality metric value may be calculated by the wireless communication device, or other device (e.g., a server or other computing device communicatively coupled to the wireless communication device) that received the signal at 402. A signal quality metric for a channel may be calculated based on a signal-to-noise ratio (SNR) of the received signal at 402 (e.g., set equal to the SNR, calculated from the SNR, representing the SNR, etc.). In some implementations, a signal quality metric value for a channel may be calculated based on a comparison of a received signal and an estimated received signal, where the estimated received signal is based on an estimated channel response for the space. For example, the signal quality metric value may be based on a value Q determined according to equation (9) above (e.g., the signal quality metric value is set equal to the value Q). In some implementations, a signal quality metric value for a channel is calculated based on the number of signals accepted or rejected by the wireless communication device (e.g., based on a quality criterion of the motion detection process). For example, the calculated signal quality metric value may be weighted based on the percentage of the signal that is accepted as input to the motion detection process over a period of time. In some implementations, a signal quality metric value for a channel is calculated based on an amount of time that a minimum number of signals are accepted as inputs to the motion detection process. For example, the calculated signal quality metric value may be weighted according to the time it takes to obtain the minimum number of accepted signals (e.g., the weight drops if it takes a longer time). In some examples, a signal quality metric value for a channel may be calculated based on the number of viable communication paths between a transmitting wireless communication device and a receiving wireless communication device (e.g., between different pairs of antennas of the device). For example, if the calculated signal quality metric value has a relatively low number of viable communication paths (e.g., less than 50% of the communication paths are considered viable as described above), the weight of the calculated signal quality metric value may be decreased. In some examples, the signal quality metric value may be determined by weighting the signal quality metric value based on two or more factors. In some implementations, the signal quality metric of the wireless communication channel is based on a value of the signal quality metric determined for each communication path between the wireless communication devices. For example, the signal quality metric value for the channel may be an average (or weighted average) of the signal quality metric values for each communication path over the channel.

At 406, it is determined whether the value of the signal quality metric meets a quality criterion for the motion detection process. In some cases, the quality criteria include a threshold value of a signal quality metric. If the signal quality metric value does not meet the quality criteria, processing proceeds to 408 where a new wireless communication channel is selected. The new wireless communication channel may be selected by the wireless communication device, or other device (e.g., a server or other computing device communicatively coupled to the wireless communication device), that received the motion detection signal at 402. In some implementations, the new wireless communication channel is randomly selected. In some implementations, the new channel is selected based on a comparison of signal quality metric values for the current wireless communication channel and the new wireless communication channel. In some examples, one or more aspects of process 500 in fig. 5 may be used in selecting a new wireless communication channel.

After selecting a new wireless communication channel, the wireless communication apparatus that transmitted or received the motion detection signal may be notified of the selected channel. For example, in the case where the receiving apparatus selects a channel, the transmitting wireless communication apparatus may be notified by the receiving wireless communication apparatus. For example, the receiving wireless communication device may communicate the selection of the selected wireless communication channel by broadcasting a message on the network representing the selected channel (e.g., a message in a packet header representing the selected channel) or via a direct connection with the transmitting wireless communication device (e.g., Wi-Fi direct). As another example, where other computing devices communicatively coupled to the wireless communication device select a channel, the computing device notifies both the sending device and the receiving device of the selected channel. For example, a removal server connected to the wireless communication devices (e.g., over the internet) may notify both wireless communication devices of the selected channel. Once the devices have been informed of the selected channel, the devices may begin transmitting motion detection signals on the selected channel and receiving signals based thereon.

If the signal quality metric satisfies the quality criterion, process 400 proceeds to 410 where the motion detection process is performed. The motion detection process may detect motion of an object in space based on the set of signals received at 402. In some instances, the motion detection process may include comparing signals received over a period of time. For example, motion may be detected based on a detected change in the frequency response of the signal received at 402, or based on a detected change in the channel response for space. In some implementations, an action or programmed response may be taken in response to detecting motion. For example, a computing device (e.g., wireless communication device 102C of fig. 1A or other device) may enable a security alert (e.g., send an alert to security personnel, a homeowner's mobile phone, or other device), enable lighting or HVAC in a location where motion is detected (e.g., in a room, hallway, or outdoors), or make a combination of these or other types of programmed responses.

After a new channel is selected and a set of new signals are received on the selected channel at 408, a signal quality metric value may be calculated for the selected channel. And may determine whether the signal quality metric satisfies a quality criterion for the motion detection process. If the signal quality metric satisfies a quality criterion, a motion detection process may be performed to detect motion based on the signal received on the selected channel. In some instances, a new channel may be pre-selected and a set of new signals received on the new channel may be used to determine a signal quality metric value. If the signal quality metric value for the new channel is greater than the signal quality metric value determined at 404, the new channel may be selected for detecting motion.

In some implementations, to avoid oscillation or reduce the oscillation frequency between two wireless communication channels (e.g., two channels having similar signal quality metric values), the channel selection criteria may include one or more of: a difference in the number of different or communicable paths on the channel, a difference in a signal quality metric value of the channel, a difference in the number of wireless communication devices seen on the channel, or a combination thereof. For example, a channel change decision may be made if one or more of the following are met: (1) the new channel may see one or more other wireless communication devices; (2) the number of communication paths on the current channel is below a threshold (e.g., 5 in the case where there are 8 potential communication paths), and the new channel has one or more additional communication paths; (3) the number of communication paths on the current channel is above a threshold (e.g., 5 in the case where there are 8 potential communication paths), the new channel has one or more additional paths, and the difference in the signal quality metric values is greater than a suitable negative threshold (e.g., -100); or (4) the number of communication paths on the current channel is above a threshold (e.g., 5 if there are 8 potential communication paths), the new channel has no more than one fewer communication paths, and the difference in the signal quality metric values is greater than a suitable positive threshold (e.g., 100). For example, if the current channel has 6 communication paths and signal quality metric values of "500" and the new channel has 7 paths and signal quality metric values of "450," the system may select the new channel through the current channel. However, if the current channel has 5 communication paths and a signal quality metric value of "500" and the new channel has 7 communication paths and a signal quality metric value of "350", the system may decide not to select the new channel because the difference in the signal quality metric values is less than the threshold "-100". As another example, if the current channel has 5 communication paths and a signal quality metric value of "500" and the new channel has 4 communication paths and a signal quality metric value of "650," the system may decide to select the new channel. However, if the current channel has 7 paths and a signal quality metric value of "550" and the new channel has 6 communication paths and a signal quality metric value of "600", the system may decide not to select the new channel because the difference in the signal quality metric values is not above the threshold value of "100".

In some implementations, the channels may be periodically checked to determine if channels other than the channel currently in use have a higher signal quality metric value. For example, at some time after a new wireless communication channel has been selected (assuming that the signal quality metric values continue to meet the quality criteria of 406), other wireless communication channels may be examined to determine whether the signal quality metric values of these channels exceed the signal quality metric value of the current wireless communication channel. In some examples, one or more aspects of process 500 in fig. 5 may be used in the periodic checks.

Fig. 5 is a flow diagram illustrating another exemplary process 500 for selecting a wireless communication channel based on a signal quality metric. The operations in the example process 500 may be performed by a data processing apparatus of a wireless communication device (e.g., the processor 114 of the example third wireless communication device 102C of fig. 1A) to detect motion based on motion detection signals received from other wireless communication devices (e.g., the wireless communication devices 102A, 102B of fig. 1A). The exemplary process 500 may be performed by other types of devices. For example, the exemplary process 500 may be performed by a system other than the third wireless communication device 102C communicatively coupled to the third wireless communication device 102C (e.g., a computer system connected to the wireless communication system 100 of fig. 1A that aggregates and analyzes motion detection signals received by the third wireless communication device 102C).

The example process 500 may include additional or different operations, and the operations may be performed in the order shown or in other orders. In some cases, one or more of the operations illustrated in FIG. 5 are implemented as a process comprising multiple operations, sub-processes, or other types of routines. In some cases, the operations may be combined, performed in other orders, performed in parallel, iterated or otherwise repeated, or performed in other ways.

At 502, a set of signals is received at a wireless communication device over a set of wireless communication channels. The wireless communication channel may be a frequency channel or a code channel, and the signal may be based on a wireless signal transmitted through the space by other (transmitting) wireless communication devices. For example, referring to the example shown in fig. 1A, the signal may be a wireless signal transmitted by one (or both) of the wireless communication devices 102A, 102B and received at the third wireless communication device 102C. In some implementations, the wireless communication device receiving the signal may be the same device that originally transmitted the wireless signal through the space. In some implementations, the received signal may be a motion detection signal based on a motion detection signal transmitted through space. The motion detection signal may be received over a wireless communication channel used for network traffic or a different wireless communication channel dedicated to motion detection.

In some implementations, the set of wireless communication channels is a subset of the available wireless communication channels. For example, in systems using some example Wi-Fi protocols, there are up to 14 frequency channels available for communication, some of which overlap with each other. The signal received at 502 may be transmitted on only a subset of the 14 channels. These channels (e.g., channels 1, 6, and 11, since they do not overlap) may be selected because the channels interact (or do not interact) with each other. In some implementations, signals are received over various available wireless communication channels.

At 504, a value of a signal quality metric is calculated for each wireless communication channel. The signal quality metric value may be calculated as described above with respect to operation 404 of fig. 4.

At 506, one of the wireless communication channels is selected from a set of wireless communication channels. The wireless communication channel may be selected by the wireless communication device, or other device (e.g., a server or other computing device communicatively coupled to the wireless communication device) that received the motion detection signal at 502. The wireless communication channel may be selected based on the signal quality metric value calculated at 504, other factors, or a combination thereof. In some implementations, for example, a number of feasible communication paths is determined for each wireless communication channel in the group, and the wireless communication channel is selected based on the signal quality metric value, the number of feasible communication paths, or both. In some implementations, a communication path may be determined to be viable based on its throughput (e.g., its throughput is above a threshold). The throughput may be determined as the total number of packets received by the device over the communication path over a period of time, or as the number of packets "accepted" (as input to the motion detection process) over the period of time. In some implementations, the number of viable wireless communication devices is determined based on the signal quality metric value and the number of viable communication paths, and the wireless communication channel is selected based on the number of viable communication devices for the channel.

After selecting a new wireless communication channel, the wireless communication device that transmitted the motion detection signal may be notified of the selected channel. The sending wireless communication device may be notified directly by the receiving wireless communication device, or by another computing device communicatively coupled to the wireless communication device. For example, the receiving wireless communication device may communicate the selection of the selected wireless communication channel by broadcasting a message on the network representing the selected channel (e.g., a message in a packet header representing the selected channel) or via a direct connection with the transmitting wireless communication device (e.g., Wi-Fi direct). As another example, a remote server connected to the wireless communication device (e.g., over the internet) may be notified of the selected channel by the receiving wireless communication device and may notify the transmitting device of the selected channel. Once the transmitting device has been informed of the selected channel, the device may begin transmitting motion-sounding signals on the selected channel.

At 508, a new set of signals is received at the wireless communication device on the wireless communication channel selected at 506. At 510, motion detection processing is performed. The motion detection process may detect motion of objects in space based on the set of signals received at 508. In some instances, the motion detection process may include a comparison of signals received over a particular time period. For example, motion may be detected based on a detected change in the frequency response of the received signal at 402 or based on a detected change in the channel response for the space. In some implementations, an action or programmed response may be taken in response to detecting motion. For example, a computing device (e.g., wireless communication device 102C of fig. 1A or other device) may enable a security alert (e.g., send an alert to security personnel, a homeowner's mobile phone, or other device), enable lighting or HVAC in a location where motion is detected (e.g., in a room, hallway, or outdoors), or make a combination of these or other types of programmed responses.

In some implementations, a new signal quality metric value may be determined for the wireless communication channel selected at 506, and the new signal quality metric may be based on the set of signals received at 508. The performance of the motion detection processing at 510 may be based on whether the new signal quality metric value satisfies the quality criteria of the motion detection processing (e.g., because the quality of the channel may be selected at 506 and changed after the signal is received at 508).

In some implementations, the process 500 may be repeated periodically. For example, after a channel has been selected, the channel may be used for motion detection until a certain amount of time has elapsed. The amount of time may be determined based on the number of feasible communication paths. For example, the amount of time (assuming 8 potential viable communication paths) may be determined according to a slow rate or a fast rate as described in table 2 below:

TABLE 2

Number of feasible communication paths	Slow rate	Fast rate of speed
			0	All the time	All the time
1	1 minute	1 minute
			2	5 minutes	1 minute
3	12 minutes	1.5 minutes
			4	15 minutes	2 minutes
5	30 minutes	4 minutes
			6	30 minutes	4 minutes
7	30 minutes	4 minutes
			8	30 minutes	10 minutes

If motion is detected by the motion detection process at 510, the periodic checks may be suspended until motion is no longer detected.

In some implementations, after a channel has been selected (e.g., at 506 in process 500), the "freshness" of the collected signals (e.g., a measure of how often the signals are received) may be analyzed after a certain amount of time (e.g., 2 minutes). After the amount of time has elapsed, a fresh scan of the selected channel may be performed and a new signal quality metric value may be calculated (e.g., to ensure that the state of the channel is still valid). If the signal quality metric or freshness satisfies a certain quality criterion, the receiving wireless communication device may notify the transmitting wireless communication device of the impending channel change and may start a countdown timer. Upon expiration of the countdown timer, the channel selection process may be repeated.

Some of the subject matter and operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Some of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on a computer storage medium for execution by, or to control the operation of, data processing apparatus. The computer storage medium may be or be included in a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Further, although the computer storage medium is not a propagated signal, the computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium may also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).

Some of the operations described in this specification may be implemented as operations performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources.

The term "data processing apparatus" encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones or combinations of the foregoing. An apparatus can comprise special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them.

A computer program (also known as a program, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. The computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language file) in a single file dedicated to the program or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

Some of the processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose integrated circuits, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and the processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include a processor for acting in accordance with instructions and one or more memory devices for storing instructions and data. A computer may also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., non-magnetic drives (e.g., solid state drives), magnetic, magneto-optical disks, or optical disks. However, the computer need not have such a device. Further, the computer may be embedded in other devices, such as a phone, a tablet, an appliance, a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, an internet of things (IoT) device, a machine-to-machine (M2M) sensor or actuator, or a portable storage device (e.g., a Universal Serial Bus (USB) flash drive). Suitable means for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices (e.g., EPROM, EEPROM, flash memory devices, etc.), magnetic disks (e.g., internal hard disk or removable disk, etc.), magneto-optical disks, and CD-ROM and DVD-ROM disks. In some cases, the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, the operations may be implemented on a computer having a display device (e.g., a monitor or other type of display device) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse, trackball, stylus, touch-sensitive screen, or other type of pointing device) by which the user may provide input to the computer. Other kinds of devices may also be used to provide for interaction with the user; for example, feedback provided to the user can be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, the computer may interact with the user by sending and receiving documents with respect to the device used by the user (e.g., by sending web pages to a web browser on the user's client device in response to requests received from the web browser).

A computer system may include a single computing device, or multiple computers operating close to or generally remote from each other and typically interacting across a communication network. The communication network may include one or more of a local area network ("LAN") and a wide area network ("WAN"), the internet (e.g., the internet), a network including satellite links, and a peer-to-peer network (e.g., an ad hoc peer-to-peer network, etc.). The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

In general aspects of some examples described, a wireless communication channel is selected based on a signal quality metric.

In a first example, a first set of signals is received at a first wireless communication device. The first set of signals is based on wireless signals transmitted through the space on a first wireless communication channel from a second wireless communication device. The method further includes calculating, by operation of the one or more processors, a value of a signal quality metric based on the first set of signals. The second wireless communication channel is selected based on a determination that the value of the signal quality metric does not meet the quality criteria of the motion detection process. A second set of signals is received at the first wireless communication device. The second set of signals is based on wireless signals transmitted through the space on a second wireless communication channel from a second wireless communication device. Motion detection processing is performed by operation of the one or more processors to detect motion of the object in the space based on the second set of signals.

In some cases, implementations of the first example may include one or more of the following features. A message representing a second wireless communication channel may be transmitted from the first wireless communication device to the second wireless communication device. The value of the signal quality metric may be based on a number of signals from the first set of signals that are rejected as input to the motion detection process based on a quality criterion of the motion detection process. The value of the signal quality metric may be based on a time period during which a minimum number of the first set of signals is accepted as input to the motion detection process. The value of the signal quality metric may include a value of a signal quality metric of the first wireless communication channel, and the value of the signal quality metric of the first wireless communication channel may be based on the values of the signal quality metrics determined for the respective communication paths between the first wireless communication device and the second wireless communication device. A difference in the number of communication paths on the first wireless communication channel and the number of communication paths on the second wireless communication channel may be calculated, and the second wireless communication channel may be selected based on the difference. The value of the signal quality metric may be based on comparing the first set of signals to an estimated received signal, and the estimated received signal may be based on an estimated channel response for the space. The first wireless communication channel and the second wireless communication channel may be frequency channels or code channels. The quality criteria may include a threshold value of a signal quality metric.

In some cases, implementations of the first example may include one or more of the following features. The value of the signal quality metric may comprise a first value and the second value of the signal quality metric may be calculated based on the second set of signals. The motion detection process may be performed based on a determination that the second value of the signal quality metric satisfies the quality criterion. The value of the signal quality metric may comprise a first value. Selecting the second wireless communication channel may include calculating a second value of the signal quality metric based on the second set of signals, and the second wireless communication channel may be selected based on a comparison of the first value and the second value.

In a second example, a first set of signals is received at a first wireless communication device. The first set of signals is based on wireless signals transmitted through the space from the second wireless communication device over a set of wireless communication channels. A value of a signal quality metric is calculated for each wireless communication channel based on the first set of signals by operation of one or more processors. One of the set of wireless communication channels is selected based on a comparison of the values of the signal quality metrics for the wireless communication channels. A second set of signals is received at the first wireless communication device. The second set of signals is based on wireless signals transmitted through the space on the selected wireless communication channel from the second wireless communication device. Motion detection processing is performed by operation of the one or more processors to detect motion of the object in the space based on the second set of signals.

In some cases, implementations of the second example may include one or more of the following features. A message may be transmitted from the first wireless communication device to the second wireless communication device indicating the selected wireless communication channel. The value of the signal quality metric may be based on a number of signals from the first set of signals that are rejected as input to the motion detection process based on a quality criterion of the motion detection process. The value of the signal quality metric may be based on a time period during which a minimum number of the first set of signals is accepted as input to the motion detection process. The quality criteria may include a threshold value of a signal quality metric. The value of the signal quality metric may be based on a value of a signal quality metric determined for each communication path between the first wireless communication device and the second wireless communication device, where each communication path includes a signal hardware path of the first wireless communication device and a signal hardware path of the second wireless communication device. The value of the signal quality metric may be based on comparing the first set of signals to an estimated received signal, and the estimated received signal may be based on an estimated channel response for the space.

In some cases, implementations of the second example may include one or more of the following features. A number of viable communication paths for communication on each wireless communication channel between the first wireless communication device and the second wireless communication device may be determined, wherein each viable communication path includes a signal hardware path of the first wireless communication device and a signal hardware path of the second wireless communication device, and selecting one of the set of wireless communication channels may be based on at least one of the number of viable communication paths of each wireless communication channel and a value of a signal quality metric of each wireless communication channel. Determining the number of feasible communication paths may be based on the throughput of the respective communication paths. Determining the number of feasible communication paths may include designating each communication path having a throughput above a threshold as a feasible communication path. For each wireless communication channel, the number of viable wireless communication devices may be determined based on a value of a signal quality metric of the wireless communication channel and the number of viable communication paths of the wireless communication channel. The wireless communication channel may be selected based on the number of viable wireless communication devices.

In a third example, a number of viable communication paths for communication over the wireless communication channel between each of the second wireless communication devices and the first wireless communication device is determined, and a value of a signal quality metric for communication over the wireless communication channel between each of the second wireless communication devices and the first wireless communication device is determined. The number of viable communication paths and the value of the signal quality metric are determined for each wireless communication channel by operation of the one or more processors and are based on wireless signals received by the first wireless communication device from a plurality of second wireless devices over a set of wireless communication channels. One wireless communication channel is selected from a set of wireless communication channels for wireless motion detection based on at least one of a number of feasible communication paths of the wireless communication channel and a value of a signal quality metric.

In some cases, implementations of the third example may include one or more of the following features. Determining the number of feasible communication paths may be based on the throughput of the respective communication paths. Determining the number of feasible communication paths includes designating each communication path having a throughput above a threshold as a feasible communication path. For each wireless communication channel, the number of viable wireless communication devices may be determined based on a value of a signal quality metric of the wireless communication channel and the number of viable communication paths of the wireless communication channel. The wireless communication channel may be selected based on the number of viable wireless communication devices.

In some implementations, a computer-readable medium stores instructions that, when executed by data processing apparatus, are operable to perform one or more operations of the first, second, or third examples. In some implementations, a system (e.g., a wireless communication device, a computer system, or other type of system communicatively coupled to a wireless communication device) includes a data processing apparatus and a computer-readable medium for storing instructions that, when executed by the data processing apparatus, are operable to perform one or more operations of the first, second, or third examples.

While this specification contains many specifics, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features specific to particular examples. Certain features that are described in this specification in the context of separate implementations can also be combined. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple embodiments separately or in any suitable subcombination.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A motion detection method, comprising:

receiving, at a first wireless communication device, a first set of signals based on wireless signals transmitted through a space on a first wireless communication channel from a second wireless communication device;

calculating, by operation of one or more processors, a value of a signal quality metric based on the first set of signals;

selecting a second wireless communication channel based on determining that the value of the signal quality metric does not meet a quality criterion for a motion detection process;

receiving, at the first wireless communication device, a second set of signals based on wireless signals transmitted through space on the second wireless communication channel from the second wireless communication device; and

the motion detection process is performed, by operation of one or more processors, to detect motion of an object in space based on the second set of signals.

2. The motion detection method according to claim 1, further comprising:

transmitting, from the first wireless communication device to the second wireless communication device, a message representing the second wireless communication channel.

3. The motion detection method according to claim 1, further comprising:

calculating a value of the signal quality metric based on a number of signals from the first set of signals that are rejected as input to the motion detection process according to a quality criterion of the motion detection process.

4. The motion detection method according to claim 3, further comprising:

calculating a value of the signal quality metric based on a time period during which a minimum number of the first set of signals is accepted as input to the motion detection process.

5. The motion detection method of claim 1 wherein the value of the signal quality metric comprises a value of a signal quality metric of the first wireless communication channel, and

the motion detection method further includes: calculating a value of a signal quality metric for the first wireless communication channel based on the determined values of the signal quality metric for each communication path between the first wireless communication device and the second wireless communication device.

6. The motion detection method according to claim 1, further comprising:

calculating a difference in the number of communication paths on the first wireless communication channel and the number of communication paths on the second wireless communication channel, wherein the second wireless communication channel is selected based on the difference.

7. The motion detection method according to any one of claims 1 to 6, further comprising:

calculating a value of the signal quality metric based on comparing the first set of signals to an estimated received signal, wherein the estimated received signal is based on an estimated channel response for the space.

8. The motion detection method according to any one of claims 1 to 6, wherein the first wireless communication channel and the second wireless communication channel are frequency channels.

9. The motion detection method according to any one of claims 1 to 6, wherein the first wireless communication channel and the second wireless communication channel are code channels.

10. The motion detection method according to any of claims 1 to 6, wherein the quality criterion comprises a threshold value of the signal quality metric.

11. The motion detection method according to any of claims 1 to 6, wherein the value of the signal quality metric comprises a first value, and

the motion detection method further includes: calculating a second value of the signal quality metric based on the second set of signals, wherein the motion detection processing is performed based on determining that the second value of the signal quality metric satisfies the quality criterion.

12. The motion detection method according to any of claims 1 to 6, wherein the value of the signal quality metric comprises a first value, and selecting the second wireless communication channel comprises:

calculating a second value of a signal quality metric based on the second set of signals; and

selecting the second wireless communication channel based on a comparison of the first value and the second value.

13. A non-transitory computer-readable storage medium storing instructions that are operable, when executed by a data processing apparatus, to perform operations comprising:

calculating a value of a signal quality metric based on a first set of signals received at a first wireless communication apparatus, the first set of signals being based on wireless signals transmitted through a space on a first wireless communication channel from a second wireless communication apparatus;

selecting a second wireless communication channel based on determining that the value of the signal quality metric does not meet a quality criterion for a motion detection process; and

performing motion detection processing to detect motion of an object in space based on a second set of signals received at the first wireless communication device, the second set of signals being based on wireless signals transmitted through space from the second wireless communication device on the second wireless communication channel.

14. The computer-readable storage medium of claim 13, the operations further comprising:

15. The computer-readable storage medium of claim 13, wherein the value of the signal quality metric is calculated based on a number of signals from the first set of signals that are rejected as input to the motion detection process according to a quality criterion of the motion detection process.

16. The computer-readable storage medium of claim 15, wherein the value of the signal quality metric is calculated based on a time period over which a minimum number of first set of signals are accepted as inputs to the motion detection process.

17. The computer-readable storage medium of claim 13, wherein the value of the signal quality metric comprises a value of a signal quality metric of the first wireless communication channel, an

The method further comprises the following steps: calculating a value of a signal quality metric for the first wireless communication channel based on the determined values of the signal quality metric for each communication path between the first wireless communication device and the second wireless communication device.

18. The computer-readable storage medium of claim 13, the operations further comprising:

19. The computer-readable storage medium of any of claims 13-18, wherein the value of the signal quality metric is calculated based on comparing the first set of signals to an estimated received signal, and the estimated received signal is based on an estimated channel response for the space.

20. The computer readable storage medium of any of claims 13 to 18, wherein the first wireless communication channel and the second wireless communication channel are frequency channels.

21. The computer readable storage medium of any of claims 13 to 18, wherein the first wireless communication channel and the second wireless communication channel are coded channels.

22. The computer-readable storage medium of any of claims 13-18, wherein the quality criteria comprises a threshold value of the signal quality metric.

23. The computer-readable storage medium of any of claims 13-18, wherein the value of the signal quality metric comprises a first value, and

the operations further include: calculating a second value of the signal quality metric based on the second set of signals, wherein the motion detection processing is performed based on determining that the second value of the signal quality metric satisfies the quality criterion.

24. The computer-readable storage medium of any of claims 13-18, wherein the value of the signal quality metric comprises a first value, and selecting the second wireless communication channel comprises:

25. A motion detection system comprising:

wireless communication devices distributed in a space, each wireless communication device including a modem configured to transmit and receive wireless signals through the space on any one of a plurality of wireless communication channels;

a data processing apparatus communicatively coupled to at least one of the wireless communication devices and configured to:

calculating a value of a signal quality metric based on a set of signals received at a first wireless communication apparatus, the set of signals being based on wireless signals transmitted from a second wireless communication apparatus on a first wireless communication channel; and

selecting a second wireless communication channel for communication between the first wireless communication device and the second wireless communication device based on determining that the value of the signal quality metric does not meet a quality criterion of a motion detection process.

26. The motion detection system of claim 25, wherein the data processing device is configured to transmit a message representative of the second wireless communication channel in response to selecting the second wireless communication channel.

27. The motion detection system of claim 25, wherein the data processing device is configured to calculate the value of the signal quality metric based on a number of signals from the first set of signals that are rejected as input to the motion detection process according to a quality criterion of the motion detection process.

28. The motion detection system of claim 25, wherein the value of the signal quality metric comprises a value of a signal quality metric of the first wireless communication channel, and

the data processing apparatus is configured to calculate a value of a signal quality metric for the first wireless communication channel based on the determined values of the signal quality metric for each communication path between the first wireless communication device and the second wireless communication device.

29. The motion detection system according to any of claims 25 to 28, wherein the data processing apparatus is configured to calculate the value of the signal quality metric based on comparing the first set of signals with an estimated received signal, the estimated received signal being based on an estimated channel response for the space.

30. The motion detection system according to any of claims 25 to 28, wherein the quality criterion comprises a threshold value of the signal quality metric.